Phenoxyacetamides for the control of pests



United States Patent 3,166,591 PHENOXYACETAMIDES FOR THE CONTROL ()FPESTS Sidney B. Richter, Chicago, 11]., assignor to Velsicol Chemical Corporation, Chicago, 111., a corporation of Illinois e No Drawing. FiletlNov. 20,1962, Ser. No. 239,072 9 Claims. (Ci. 260- 559) 01 V wherein X is selected from the group consisting of hydro gen, and substituted and unsubstituted alkyl groups, Y is selected from the group consisting of substituted and unsubstituted alkyl groups, and Z is'an unsubstituted alkylene group containing from one to four carbon atoms. In a preferred embodiment of this invention, Z is as described above, X is selected from the group consisting of hydrogen and unsubstituted alkyl groups containing from one to ten carbon atoms, and Y is an unsubstituted alkyl group containing from one to ten carbon atoms.

The novel alkoxy amides of the present invention can be prepared convenientlyrfrom the corresponding acid, which is often commercially available, or can be synthesized by treating the corresponding 2,4-dichlo10phen0l with an alkali metal hydroxide to form the salt, and treating the salt with a bromo-alkyl acid of the formula wherein Z is as described above, or a loweralkyl ester of the acid, and then hydrolyzing. Alternatively, free acids, other than 2,4-dichlorophenoxy-acetic acids, can be prepared from the corresponding2,4-dichlorophenoxyalkyl acid wherein Z has one less --CH group attached to the COOH group than in the desired free acid, by reducing the lower acid with lithium aluminurn'hydride at a low temperature, treating theresulting' alcohol with a to be satisfactory. The treatment is performed by heat thionyl chloride to obtain the halide, treating the halide with sodium cyanide andthen-hydrolyzing the product to obtain the free acid.

Examples of the free acids from which the compounds of the present invention can beprepared, are: 2,4-dichlorophenoxy acetic acid, lit-(2,4-diCh1OI'OPh5Il0XY) propionic acid, fl-(ZA-dichlbrophenoxy) propionic acid, (IL-(2,4- dichlorophenoxy) n -butyric acid, ,B-(2-4 dichlorophenoxy)-n-butyric acid, 'y'-(2,4-dichlorophenoxy)-n-butyric acid, a-(2,4-dichlorophenoxy)-isobutyric acid, a-(ZA-dichlorophenoxy)-n-valeric acid, 'y-(2-4-dichlorophenoxy)- n-valeric acid, 6.-(2,4-dichlorophenoxy -n-valericacid, and the like.

The free acid can then be converted toitsacid chloride, which is treated with an alkoxyamine of the formula tents wereh'eated to reflux, and stirring was continued wherein X and Y areas described above, to give the" Bdbdfihl Patented Jan. 19, 1965 desired compound of the present invention. Suitable amines of the above formula can be prepared, for example, by the reduction of the corresponding oximes as described by Jones and Major, J. Am. Chem. Soc., vol. 52, pp. 669 79 (1930). Exemplary of suitable alkoxy amines useful as a reactant to prepare the N-alkoxy amides of the present invention, are: N-methoxyamine, N-methoxy-N-methylamine, N-ethoxyamine, N-ethoxy-N-methylamine, N- ethoxy-N-ethylamine, N-methoxy-N-ethylamine, N-n-propoxyamine, N-isopropoxyamine, N-n-propoxy-N-ethylamine, and the like. c

More particularly, the free acid is treated with an equimolecular or greater quantity of thionyl chloride, preferably in a solvent or diluent, such as benzene. An amount of solvent or diluent approximately equal in volume to the Volume of the free acid has been found ing for several hours, preferably at reflux if a solvent or diluent, such as benzene, or a large excess of thionyl chloride is used. The corresponding acyl chloride thus formed can be isolated from the reaction mixture by means common to the art, such as by distillation of the solvent or diluent and unreacted reactants, leaving the acyl chloride as the residue.

In the second step, the acyl chloride is reacted with an equimolecular or greater amount of the appropriate N-alkoxyamine or preferably its hydrochloride, in the presence of a base, such as sodium hydroxide, potassium hydroxide, and potassium carbonate. At least one equivalent quantity of base, is used when the free amine is utilized as the reactant, and at least twice' that amount is'used when the amine hydrochloride is used as the reactant. The base is used to release the amine from its hydrochloride, and to neutralize the hydrogen chloride, formed during the reaction. A small amount of water is preferably added to the reaction mixture to form an aqueous solution of the base to aid in mixing the base into the solution of the amine or amine-hydrochloride reactant. The reaction is conveniently performed utiliz ing a solvent or diluent, such as benzene, by heating for several hours preferably at reflux temperature when a solvent or diluent is used. When potassium carbonate .the desired product as the residue. The N-alkoxy amide compound of the present invention thus obtained can be used for manyapplications as such, or can be recrystal lized from a suitable solvent.

The manner in which the new compounds of this in- 1 vention can 'be preparedis illustrated in the following examples.

EXAMPLE 1 v Preparation of 2,4-dichl0ropheltoxyacetyl chloride 2,4-dichlorophenoxyacetic acid (110.5 g.; 0.55 mol) and tents of thejflask were stirredand thionyl chloride :(40

ml.; 0.55 mol) was slowly added tothe flask. The conat reflux for-four hours. The reaction mixturewas dried over magnesium sulfate, filtered and distilled under reduced pressure'to remove benzene and unreacted thionyl chloride. I The residue was distilled in vacuo to yield the 3 product 2,4-dichlorophenoxyacetyl chloride, as a clear light yellow liquid boiling at 106-110" C. at 0.45 mm. Hg pressure.

EXAMPLE 2 Preparation of N-methoxy-N-methyl-2,4- dichlorophenoxyacetamide N-methoxy N methylamine-hydrochloride (7.41 g.; 0.076 mol), potassium carbonate (11.6 g.; 0.084 mol), and diethyl ether (75 ml.) were placed in a 300-ml., threenecked, round-bottom flask, equipped with a mechanical stirrer, reflux condenser, and dropping'funnel. The mixture was stirred, and 2,4-dichlorophenoxyacetyl chloride (18.2 g.; 0.076 mol), prepared in Example 1, was slowly added to the flask. The reaction was exothermic, and the mixture was stirred at reflux for 7 hours. The reaction mixture was filtered and the solids Washed thrice with diethyl ether. The ether washings were combined with the filtrate, dried over magnesium sulfate, filtered, and the filtrate distilled under reduced pressure to remove solvent and to yield a white solid residue. This residue was recrystallized from hexane and dried to give the product N-methoxy-N-methyl-2,4-dichlorophenoxyacetamide melting 72-75 C., and having the following. elemental analysis.

Calculated for C H Cl NO Preparation of N-methoxy-2,4-dichlorophenoxyacetamide Methoxyamine-hydrochloride (6.7 g.; 0.08 mol), potassium carbonate (12.2 g.; 0.088 mol), diethyl ether (100 ml.) and water (5 ml.) were placed in a 300 ml. threenecked, round-bottom flask fitted with a mechanical stirrer, reflux condenser and dropping funnel. The mixture was stirred, and 2,4-dichlorophenoxyacetyl chloride (19.2 g.; 0.08 mol), prepared in Example 1, was slowly added to the flask. The reaction was exothermic, and the mixture was stirred at reflux for 6 /2 hours. The reaction mixture was filtered and the solids washed three times with diethyl ether. The ether washings were combined with the filtrate, and the mixture was dried 'over magnesium sulfate, and filtered. The filtrate therefrom was distilled under reduced pressure to remove diethyl ether to yield a white solid residue which was recrystallized from hexane and dried to yield solid N-methoxy- 2,4-dichlorophenoxyacetamide, melting 101-2 C. and having the following elemental analysis.

Calculated for C9H9C12NO3:

Preparation of N-ethxy-2,4-dichlorophenoxyacetamide The product of Example 1 is reacted with ethoxyaminehydrochloride according to the technique of Example 3 to yield N-ethoxy-2,4-dichlorophenoxyacetamide.

EXAMPLE 5 Preparation of ot-(N-n-propoxy-N-methyl-2,4-dicltlar0- phen0xy)-propionamia'e V a-(2',4-dich1orophenoxy)-propionic acid, which can be prepared by treating 2,4-dichlorophenol with sodium hydroxide and then a-bromopropionic acid, is treated with thionyl chloride by the procedure of Example 1 to obtain a-(2,4-dichlorophenoxy)-propionyl chloride. This latter 4- intermediate is reacted with N-n-propoxy-N-methylamine-hydrochloride by the technique of Example 2 to yield the desired product a-(N-n-propoxy-N-methyl-Z,4- dichlorophenoxy) -propionamide.

EXAMPLE 6 Preparation of 'y-(N-metlz0xy-2,4-dichl0rophenoxy)- n-butyramide -(2,4-dichlorophenoxy)-n-butyric acid, which can be prepared by treating 2,4-dich1orophenol with sodium hydroxide and then y-bromo-n-butyric acid, is treated with thionyl chloride by the procedure of Examyle 1 to obtain -(2,4-dichlorophenoxy)-n-butyryl chloride. This intermediate is reacted with methoxyamine-hydrochloride according to the technique of Example 3 to yield the desired product y-(N-methoxy-2,4-dichlorophenoxy)-nbutyramide.

EXAMPLE 7 Preparation of 6-(N-etlzoxy-N-ethyl-2,4-dichlor0- phenoxy)-n-valeramide 5-(2,4-dichlorophenoxy)-n-valeric acid, which can be prepared by treating 2,4-dichl0rophenol with sodium hydroxide, and then fi-bromo-n-valeric acid, is treated with thionyl chloride by the method of Example 1 to obtain 6-(2,4-dichlorophenoxy)-n-valeryl chloride. This intermediate is reacted with N-ethoxy-N-ethylamine-hydrochloride according to the procedure of Example 2 to yield the desired product 8-(N-ethoxy-N-ethyl-2,4-dichlorophenoxy) -n-valeramide.

Other compounds within the scope of the present invention can be prepared in the manner detailed in the previous examples. Given in Examples 8-16 are the free acid and the amine reactants which can be used to prepare the indicated named compounds of this invention.

EXAMPLE 8 fl-(2-4-dichlorophenoxy)-n-butyric acid-l-N methoxy- Nn-butylamine=[3-(N methoxy-N-n-butyl-2,4-dichlorophenoxy) -n-butyramide.

EXAMPLE 9 a-(2,4-dichlorophenoxy)-isobutyric acid-l-N-ethoxy-N- n-propylamine=a-(N-ethoxy-N-n-propyl 2,4 dichlorophenoxy)-is'obutyramide.

EXAMPLE 10 ,B-(2,4-dichlorophenoxy) n propionic acid-l-N-methoxy-N-methylamine=5-(N-methoxy N methyl-2,4-dichlorophenoxy) -n-propionamide.

EXAMPLE 1 1 2,4-dichlorophenoxyacetic acid+n-butoxyamine=N-nbutoxy-2,4-dichlorophenoxyacetamide.

EXAMPLE -12 'y-(2,4-dichlorophenoxy)-n-valeric acid+N methoxy- N methylamine='y-(N-methoxy-N-methyl-2,4-dichlorophenoxy)-n-valeramide.

EXAMPLE 13 EXAMPLE 14 a-(2,4 dichlorophenoxy)-n-butyric acid+N-methoxy N methylamine ov(N-methoxy-N-methyl-Z,4-dichloro phenoxy) -n-butyramide.

EXAMPLE fl-(ZA-dichlorophenoxy) isopropionic acid-l-N-methoxy N methylamine=,8-(N-methoxy-N-methyl-Z,4-dichlorophenoxy) -isopropionamide.

EXAMPLE 16 a- (2,4-dichlorophenoxy)-iso-butyric acid+N-methoxy- N methylamine=w(N-rtrethoxy-N-methyl-Z,4-dichlorophenoxy)-isobutyr'amide.

For practical use as pre-emergence herbicides, the compounds of this invention are generally incorporated into herbicidal compositions which comprise an inert carrier and a herbicidally toxic amount of such a compound. Such herbicidal compositions, which are usually known in the art as formulations, enable the active compound to be applied conveniently to the site of the soil to be treated in any desired quantity. These compositions can be solids such as dusts, granules, or wettable powders; or they can be liquids such as solutions or emulsifiable concentrates.

For example, dusts can be prepared by grinding and blending the active compound with a solid inert carrier such as the talcs, clays, silicas, pyrophyllite, and the like. Granular formulations can be prepared by impregnating the compound, usually dissolved in a suitable solvent,

on to and into granulated carriers such as the attapulgites or the vermiculites, usually of a particle size range of from about 0.3 to 1.5 mm. Wettable powders, which can be dispersed in Water to any desired concentration of the active compound, can be prepared by incorporating wetting agents into concentrated dust compositions.

In some cases the active compounds are sufficiently solu ble in common organic solvents such as kerosene or xylene so thatthey can be used directly as solutions in thesesolvents. However, preferred liquid herbicidal compositions are emulsifiable concentrates, which comprise an active EXAMPLE 17 Preparation of a dust Product of Example 2 10 Powdered talc 90 The above ingredients are mixed in a mechanical grinder-blender and are ground until a homogeneous, free-flowing dust of the desired particle size is obtained. This dust is suitable for direct application to the site of the weed infestation.

The pre-emergence herbicides of this invention can be applied in any manner recognized by the art. The concentration of the new compounds of this invention in the herbicidal compositions will vary greatly with the type of formulation and the purpose for which it is designed, but generally the herbicidal compositions will comprise from about 0.05 to about 95 percent by weight of the active compounds of this invention. In a preferred embodiment of this invention, the herbicidal compositions will comprise from about 5 to about 75 percent by weight of the active compound. The compositions can also comprise such additional substances as other pesticides, spreaders, adhesives, stickers,,fertilizers activators, synergists,;.and the like;

, is esonomically desirable to control the growth of such fering with the production of cultivated crops or with the welfare of livestock. Many types of weeds are known, including annuals such as pigweed, lambs-quarters, yellow foxtail, crabgrass, wild mustard, French-weed, rye grass, goose-grass, chickweed, and smartweed; biennials such as wild carrot, great burdock, mullein, round-leaved mallow, blue thistle, bull thistle, hounds-tongue, moth mullein, and purple star thistle; or perennials such as white cockle, perennial rye-grass, quack-grass, Johnson grass, Canada thistle, hedge bindweed, Bermuda grass, sheep sorrel, field chickweed, and winter-cress. Similarly, such weeds can be classified as broad-leaf or grassy weeds. It

' valuable for weed control because they are toxic to many species and groups of weeds while they are relatively non- 'toxic to many benefical plants. The methods of this invention for the control of weeds comprises applying tothe soil containing weed seeds and seedlings, a herbicidal composition comprising an inert carrier and as the essential active ingredient, in a quantity which is herbicidally toxic to said weed seeds and/ or seedlings, a compound of this invention. Application of the herbicidal composition is preferably made to the soil at or before the time of planting or between planting and the emergence of desirable plants. Where the soil is to be treated between planting and emergence of desirable plants, it is preferred to plant the seeds of desirable plants below the zone of the weed seeds. The exact amount of compound required will depend on a variety of factors including the hardiness of the pounds of the-active compound per acre. Duplicate particular weed species, weather, method of application,

the kind of beneficial plant seeds in the same area, and the like. Thus, while the application of up to only about one or two ounces of an active compound per acre may be suflicient for good control of a light infestation of weeds under adverse conditions, the application of one poundor more of active compound per acre may be required for paper pots filled with a sand and soil mixture are seeded with weeds; and immediately after seeding,'the soil surface of each pot is sprayed with an appropriately diluted test solution. The weed growth is maintained under artificial. lighting with irrigation provided by placing the porous pots in a small amount of water in stainless steel trays. The Weeds are observed for a week to ten days; and the percent kill, injury, and stand reduction are recorded. The results indicate a high order of preemergence herbicidal activity of the compounds of this invention. used.

Comparable pro-planting tests can also be nsuallykilled or seriously weakened. When the crabgrass Weeds are undesirable plants :in their growing where they are not wanted, having no economic value, and interweed pestsof lawns are Digitaria ischaemum, commonly known as smooth crabgrass, and Digz'mria sanguinalis, usually known as common, large, hairy, tall, purple, finger- The pre-emergence herbicidal activity of the com- The grasses around each crabgrass plant are grass, turkeyfoot, crowfoot grass, and watergrass. At least fifteen other varities of Digitaria species of crabgrass are known. Also generally classified with crabgrass are such weeds as goosegrass (Elcusine indica), broomsedge (A ndropogon virgz'm'cus), pigeon grass or green bristle grass (Setaria viridis), yellow bristle grass (Sctaria Iutescens), watergrass (Echinochloa crusgalli), witchgrass (Punicum capillare), cheatgrass or chess (Bro/nus secrzlinus), and downy broomgrass (Bromus tectorum) p In one series of tests, filter paper was dipped in acetone solutions of the test compounds at various concentrations. The paper was then dried, and small pieces were placed on the bottom of plastic dishes having a film of agar nutrient and a row of crabgrass seeds set apart from the treated filter paper. The seeds were allowed to germinate under controlled laboratory conditions, and the toxicity of the chemical compounds was determined on the basic of the primary root length of the germinated seedlings, short root lengths being indicative of high toxicity to crabgrass. The results of these tests are summarized in the following table:

Primary root lengthsin mm. at conens.

in ppm. of 7 Test Chemical N-metl1oxy-N-metl1yl-2,4-

dichlorophenoxyacotamide wherein X is selected from the group consisting of hydrogen and alkyl containing from one to ten carbon atoms,

Y is alkyl containing from one to ten carbon atoms, and Z is unsubstituted alkylene containing from one to four carbon atoms.

2. A compound of the formula References Cited in the file of this patent UNITED STATES PATENTS 2,723,192 Todd NOV. 8, 1955 2,726,150 Wolter Dec. 6, 1955 2,832,767 Boettner Apr. 29, 1958 2,911,440 Thullier et a1 Nov. 3, 1959 2,948,754 Litvan et a1. Aug. 9, 1960 3,027,407 Major et al Mar. 27, 1962 3,029,277 Metivier Apr. 10, 1962 FOREIGN PATENTS 875,807 Germany May 7, 1953 OTHER REFERENCES Eckstein et 211.: Chemical Abstracts, vol. 52, pages 16,61616,617(1953).

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 5,166,591 January 19, 1965 Sidney B. Richter It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 6 line 13, for "esonomically" read economically column 7, in the table, sixth column, line 1 thereof, for "9 83" read O .83

Signed and sealed this 20th day of July 1965.

(SEAL) Attest:

EDWARD J. BRENNER.

Commissioner of Patents ERNEST W. SWIDER Attesting Officer 

1. A COMPOUNDS OF THE FORMULA 